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<head>
  <meta charset="UTF-8">
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  <title>Document</title>
</head>
<body>
  
  <script>

    // JavaScript只支持单继承(不支持多继承)
    function mixinAnimal(BaseClass) {
      return class extends BaseClass {
        running() {
          console.log("running~")
        }
      }
    }

    function mixinRunner(BaseClass) {
      return class extends BaseClass {
        flying() {
          console.log("flying~")
        }
      }
    }

    class Bird {
      eating() {
        console.log("eating~")
      }
    }

    // var NewBird = mixinRunner(mixinAnimal(Bird))
    class NewBird extends mixinRunner(mixinAnimal(Bird)) {
    }
    var bird = new NewBird()
    bird.flying()
    bird.running()
    bird.eating()

  </script>

</body>
</html>